Signs and Treatment of Swimmers Itch

Table of Contents

First identified in Douglas Lake, in Michigan, USA, over 70 years
ago, swimmers itch (also referred to as cercarial dermatitis, duck itch
and schistosome cercarial dermatitis) is a common problem among those
that enjoy natural waterways such as lakes, rivers and ponds.

The
condition is caused by a parasite; small worms that bury themselves
beneath the skin and die. The worms die because birds and snails are
natural hosts, while humans are not.

The swimmer's itch is actually
an allergic reaction to the worms. The rash and itch reaction, which
happens within hours to days, is typically short-lived; usually about a
week. Symptoms will appear in up to 2 days after being exposed. Swimming
pools that are properly chlorinated do not spread this condition.

Most
people do not show any allergic skin reaction when exposed to the
protein that causes this condition, so it is possible to see no symptoms
or different symptoms from person to person. It is not contagious and most people do not require medical attention.

Swimmer's Itch on Leg

What Is Swimmer's Itch?

Swimmer's itch is an allergic reaction to a parasite that burrows into the skin. It is found in all bodies of natural water such as oceans, ponds, and lakes.

Other Names

Is Swimmer's Itch Contagious?

Swimmer's Itch is not contagious.

Causes

Swimmers Itch Worm (Cercariae of Austrobilharzia variglandis)

The causes of swimmer’s itch are related to a variety of flatworm
parasites, which belong to the Schistosomatidae family. These little
critters use hosts, such as snails and birds, to complete their
lifecycles, but at one point during their cycle, they leave one host to
search for another. If you’re swimming and get in their way, they end
up burrowing under your skin, where they die once you leave the water.

Their death causes your body’s immune system to respond by breaking out
in a red and extremely itchy rash. While it may start out as a mild
reaction, it typically escalates and the initial red “spots” become
bumpy papules. Each bump is the graveyard of a flatworm that penetrated
your skin after you were done swimming.

Lifecycle

Swimmer's Itch Worm Lifecycle Diagram

Hosts of the worm that causes swimmer's itch, such as geese,
ducks, shorebirds or seaguls have adult worms in the blood vessels.
These worms spread eggs that are passed via the feces.

When the
eggs are exposed to water, they hatch and produce a ciliated miracidium
(baby worm) that infects a snail (gastropod) as an intermediate host.

The
parasite develops in the snail to provide what are called "free
swimming cercariae" which are worms that are released. These worms
penetrate the skin of any nearby birds and move to the blood vessels.

When
humans are present instead of snails, the worms will be attracted to
the human skin and burrow in when the person leaves the lake as a means
of survival during the water evaporation process. Areas, where water
collects and gives the worms more time to burrow, such as leg openings
or at the waist of a bathing suit, are more susceptible to the "swimmer's
itch."

Swimmer's Itch FAQ Video

Symptoms

The first signs that you may have swimmer’s itch will be a red rash
that may or may not itch severely. Not all people react to swimmer’s
itch in the same way and some may develop a mild irritation to a severe
and horrendously itchy red rash. If you do scratch it too much, you run
the risk of infection.

The degree of your symptoms will largely depend on how many of the worm
larvae you get on your skin and how sensitive you happen to be to them.
The more you are in the contaminated water, the worse your symptoms may be.
Typically, symptoms also get worse with repeated exposure.

Swimmer's Itch on Upper Leg or Thigh

Some people will start itching virtually the moment you dry off after getting
out of the water, as that is when the larvae burrow into your
skin. Other will see symptoms such as pimples within 12 hours.

You may feel an odd tingly, burning sensation as the larvae start
to get under your skin and it may start immediately. Shortly
afterwards, you may also see small red dots that will blossom into a
larger red rash as time passes. The initial tingle will typically be
replaced by a nagging itch that mimics an insect bite or being stung by
nettles.

Not everyone that comes into contact with the protein in the cercaria
that triggers the condition will have a skin reaction (estimated at 30%
to 40% of all people show a reaction).

Symptoms May Include:

Small blisters

Red pimples

Itch

Tingling

Burning

Does Swimmer's Itch Leave Scars?

Swimmer's itch does not leave scars. In most cases, it will clear up on its' own.

Diagnosis

Your doctor will want to know what you have been doing before you broke
out into a rash. Once you mention swimming, they will typically give
your rash a closer inspection for the telltale signs of swimmer’s itch:
small red pimples that may develop into blisters. There are no specific
blood tests available to test fo rthe condition.
Unfortunately, you
may be itching for up to a week, but there are things you may do to
ease the swimmer’s itch.

Swimmer's Itch on Arm

It is possible that the diagnosis for swimmer's itch can get confused
with other skin conditions such as herpes, poison ivy, chicken pox or a
bacterial skin infection (impetigo).

Swimmer's Itch vs. Chicken Pox

Swimmer's itch looks like chicken pox, but it usually isn't seen in areas that would be covered by a bathing suit. If you do see symptoms in these areas, consider causes such as Chicken Pox or insect bites.

Swimmer's Itch vs. Chicken Pox. The Chicken Pox (top) goes through three stages, from bumps on the skin, to blisters and then crusts and scabs. Swimmer's Itch lasts up to a week and will gradually go away on its' own.

Treatment and Remedies

Most cases of swimmer itch will dissipate on its own, but if you do
scratch and it gets worse, see your doctor for help. There are
certainly several things you may try at home:

There is no way to completely prevent swimmer's itch.
The risk can be reduced by avoiding shallow water (if
swimming off a boat, move into deeper water), towel
drying after leaving the water, and avoid feeding and attracting water
fowl such as geese. More information is
available on this swimmers
itch fact sheet (PDF download).

The application of copper sulfate will reduce the snail population,
which will temporarily reduce the incidence of this problem.
Use of this product in waterways is tightly regulated and
must be approved by your local fisheries office.

When To Call The Doctor

Call a Doctor if the entire body is covered with skin reactions or if the swimmer itch is very irritating. A Doctor will treat swimmer itch with an antihistamine or topical cortisone cream.

Swimmer's Itch on Legs

Prevention

For prevention, beware of any posted warning signs. Avoid marshy areas where there are snails. After leaving the water wash off immediately and quickly towel dry. Some parasites enter the skin as the water dries.